Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é o ano médio para Ayan Mukerji?
 ###Tabelas: CREATE TABLE 2.ukrainians (2.ukrainians_id AUTO_INCREMENT PRIMARY KEY, C/W 15+ INT, Oblast\Age VARCHAR, 15 to 17 INT, 18 to 19 VARCHAR, 20 to 24 INT, 25 to 29 INT, 30 to 34 INT, 35 to 39 INT, 40 to 44 INT, 45 to 49 INT, 50 to 54 INT, 55 to 59 INT, 60 to 64 INT, 65 to 69 INT) CREATE TABLE highest-grossing_bollywood_films_worldwide (highest-grossing_bollywood_films_worldwide_id AUTO_INCREMENT PRIMARY KEY, Rank INT, Movie VARCHAR, Year INT, Worldwide Gross VARCHAR, Director VARCHAR, Verdict VARCHAR) CREATE TABLE winners_of_the_allaire_dupont_distaff_stakes_since_1992 (winners_of_the_allaire_dupont_distaff_stakes_since_1992_id AUTO_INCREMENT PRIMARY KEY, Year INT, Winner VARCHAR, Jockey VARCHAR, Trainer VARCHAR, Owner VARCHAR, Distance VARCHAR, Time VARCHAR, Purse VARCHAR) CREATE TABLE water_parks_in_terms_of_attendance (water_parks_in_terms_of_attendance_id AUTO_INCREMENT PRIMARY KEY, Rank INT, Water park VARCHAR, Location VARCHAR, 2011 INT, 2012 INT) CREATE TABLE 1850_1871 (1850_1871_id AUTO_INCREMENT PRIMARY KEY, Class VARCHAR, Wheel arrangement VARCHAR, Manufacturer VARCHAR, Year made VARCHAR, Quantity made VARCHAR, Quantity preserved VARCHAR, Year(s) withdrawn VARCHAR)  
SELECT AVG Year FROM highest-grossing_bollywood_films_worldwide WHERE Director = ayan mukerji